U.S. patent application number 13/383635 was filed with the patent office on 2012-06-21 for method for the production of a multilayer element, and multilayer element.
This patent application is currently assigned to LEONHARD KURZ STIFTUNG & CO. KG. Invention is credited to Ludwig Brehm, Rene Staub.
Application Number | 20120156446 13/383635 |
Document ID | / |
Family ID | 42668044 |
Filed Date | 2012-06-21 |
United States Patent
Application |
20120156446 |
Kind Code |
A1 |
Brehm; Ludwig ; et
al. |
June 21, 2012 |
Method for the Production of a Multilayer Element, and Multilayer
Element
Abstract
The invention relates to a method for producing a multilayer
element (100), and also to a multilayer element (100) produced by
said method. On and/or in a carrier ply (1) a decorative ply (3) is
formed. The decorative ply (3) has a first region (8) and a second
region (9). Viewed perpendicular to the plane of the carrier ply
(1), the decorative ply (3) has in the first region (8) a first
transmittance and in the second region (9) a second transmittance
greater in comparison to the first transmittance. A layer (5) to be
structured and a photoactivatable resist layer are disposed on the
first side (11) of the carrier ply (1). On exposure of the resist
layer through the decorative ply (3), the decorative ply (3) serves
as an exposure mask. The at least one layer (5) to be structured
and the resist layer are structured in register to one another by
means of structuring operations synchronized with one another.
Inventors: |
Brehm; Ludwig; (Adelsdorf,
DE) ; Staub; Rene; (Hagendorn/Schweiz, CH) |
Assignee: |
LEONHARD KURZ STIFTUNG & CO.
KG
Furth
DE
|
Family ID: |
42668044 |
Appl. No.: |
13/383635 |
Filed: |
July 13, 2010 |
PCT Filed: |
July 13, 2010 |
PCT NO: |
PCT/EP10/04251 |
371 Date: |
March 1, 2012 |
Current U.S.
Class: |
428/195.1 ;
427/553; 428/212; 428/213 |
Current CPC
Class: |
Y10T 428/2495 20150115;
B42D 25/328 20141001; Y10T 428/24612 20150115; Y10T 428/24868
20150115; B42D 25/47 20141001; Y10T 428/24942 20150115; B42D 25/45
20141001; Y10T 428/24802 20150115; B42D 25/41 20141001; B42D 25/445
20141001; Y10T 428/24521 20150115; Y10T 428/24835 20150115; Y10T
428/24529 20150115 |
Class at
Publication: |
428/195.1 ;
427/553; 428/212; 428/213 |
International
Class: |
B32B 3/00 20060101
B32B003/00; B32B 7/02 20060101 B32B007/02; C08J 7/18 20060101
C08J007/18 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 17, 2009 |
DE |
102009033762.8-45 |
Claims
1. A method for producing a multilayer element, where a) on and/or
in a carrier ply having a first side and a second side, a
single-layer or multilayer decorative ply having a first region and
a second region is formed, the decorative ply, viewed perpendicular
to the plane of the carrier ply, having in the first region, a
first transmittance and in the second region a second transmittance
greater in comparison to the first transmittance, said
transmittances relating to electromagnetic radiation having a
wavelength suitable for photoactivation, b) at least one layer to
be structured is disposed on the first side of the carrier ply, c)
a resist layer which can be photoactivated by means of said
electromagnetic radiation is disposed on the first side of the
carrier ply in such a way that the resist layer is disposed on the
side of the at least one layer to be structured that is remote from
the carrier ply, and the decorative ply is disposed on the other
side of the at least one layer to be structured, d) the resist
layer is exposed from the second side of the carrier ply by means
of said electromagnetic radiation, the decorative ply serving as an
exposure mask through the design of the first region and of the
second region, and e) the at least one layer to be structured and
the resist layer are structured in register with one another by
means of structuring operations synchronized with one another.
2. The method as claimed in claim 1, wherein the decorative ply
comprises a first coating layer which is disposed in the first
region with a first layer thickness and in the second region either
not or with a second layer thickness smaller in comparison to the
first layer thickness on the carrier ply, so that the decorative
ply has said first transmittance in the first region and said
second transmittance in the second region.
3. The method as claimed in claim 1, wherein the decorative ply
comprises a first coloration of the carrier ply, which is formed in
the first region with a first layer thickness and in the second
region either not or with a second layer thickness smaller in
comparison to the first layer thickness, so that the decorative ply
has said first transmittance in the first region and said second
transmittance in the second region.
4. The method as claimed in claim 1, wherein the layer thickness
and the material of the decorative ply are selected such that the
first transmittance is greater than zero.
5. The method as claimed in claim 1, wherein the thickness and the
material of the decorative ply are selected such that the ratio
between the second transmittance and the first transmittance is
greater than two.
6. The method as claimed in claim 1, wherein a detachment layer
and/or a protective coating layer, is disposed between the carrier
ply and the at least one layer to be structured.
7. The method as claimed in claim 6, wherein the thickness and the
material of the decorative ply are selected such that the
electromagnetic radiation, measured after passage through a layer
stack consisting of the carrier ply, the at least one functional
layer and the decorative ply, has a transmittance of around 0.3 in
the first region and a transmittance of around 0.7 in the second
region.
8. The method as claimed in claim 1, wherein on the first side of
the carrier ply, at least one relief structure is formed, and
wherein the at least one layer to be structured is disposed on the
surface of the at least one relief structure.
9. The method as claimed in claim 8, wherein a replicating layer is
disposed on the first side of the carrier ply, and wherein in that
the at least one relief structure is embossed into a surface of the
replicating layer that is remote from the carrier ply.
10. The method as claimed in claim 8, wherein the at least one
relief structure is embossed into the carrier ply.
11. The method as claimed in claim 8, wherein the at least one
relief structure is disposed at least partly in the first region
and/or in the second region.
12. The method as claimed in claim 1, wherein, after step e), a
compensating layer is applied on the first side of the carrier
ply.
13. The method as claimed in claim 1, wherein at least one layer of
the decorative ply is applied on the second side of the carrier
ply.
14. The method as claimed in claim 13, wherein the at least one
layer of the decorative ply that is applied on the second side of
the carrier ply is removed from the carrier ply after exposure step
d).
15. The method as claimed in claim 1, wherein the photoactivatable
layer is formed using a positive photoresist whose solubility
increases on activation by exposure, or a negative photoresist
whose solubility decreases on activation by exposure, and wherein
the resist layer is removed in the second region when a positive
photoresist is used or is removed in the first region when a
negative photoresist is used.
16. The method as claimed in claim 15, wherein the layer to be
structured is removed in the first or second region in which the
resist layer has been removed.
17. The method as claimed in claim 1, wherein UV radiation is used
for exposure step d).
18. A multilayer element having a carrier ply which has a first
side and a second side, and a single-layer or multilayer decorative
ply formed on and/or in the carrier ply, the decorative ply having
a first region and a second region and, viewed perpendicular to the
plane of the carrier ply, having in the first region a first
transmittance and in the second region a second transmittance
greater in comparison to the first transmittance, said
transmittances relating to electromagnetic radiation having a
wavelength suitable for photoactivation, the multilayer element
also having at least one layer which is structured in register to
the first region and the second region.
19. The multilayer element as claimed in claim 18, wherein the
multilayer element in the first region or the second region has a
resist layer which is photoactivatable by means of said
electromagnetic radiation, the at least one structured layer and
the resist layer being disposed in in-register orientation to one
another in such a way, on the first side of the carrier ply, that
the resist layer is disposed on the side of the at least one
structured layer that is remote from the carrier ply, and the
decorative layer is disposed on the other side of the at least one
structured layer.
20. The multilayer element as claimed in claim 18, wherein the
decorative ply comprises a first coating layer which is disposed in
the first region with a first layer thickness and in the second
region either not or with a second layer thickness smaller in
comparison to the first layer thickness on the carrier ply, so that
the decorative ply has said first transmittance in the first region
and said second transmittance in the second region.
21. The multilayer element as claimed in claim 18, wherein the
decorative ply comprises a first coloration of the carrier ply,
which is formed in the first region with a first layer thickness
and in the second region either not or with a second layer
thickness smaller in comparison to the first layer thickness, so
that the decorative ply has said first transmittance in the first
region and said second transmittance in the second region.
22. The multilayer element as claimed in claim 18, wherein the
decorative ply is at least partly transparent to visible light
having a wavelength in a range from approximately 380 to 750
nm.
23. The multilayer element as claimed in claim 18, wherein the
decorative ply is colored with at least one opaque and/or at least
one transparent colorant which at least in one wavelength range of
the electromagnetic spectrum is chromatically colored or
chromatically color-generating, and wherein the colorant can be
excited outside the visible spectrum and generates a visually
perceptible colored impression.
24. The multilayer element as claimed in claim 18 wherein the
decorative ply is colored with at least one colorant in the color
yellow, magenta, cyan or black or in the color red, green or blue,
and/or is provided with at least one red and/or green and/or blue
fluorescent, radiation-excitable pigment or dye and thereby
generates an additive color on irradiation.
25. The multilayer element as claimed in claim 18 wherein the first
transmittance is greater than zero.
26. The multilayer element as claimed in claim 18 wherein the ratio
between the second transmittance and the first transmittance is
greater than two.
27. The multilayer element as claimed in claim 18, wherein, on the
first side of the carrier ply, at least one relief structure is
formed and the at least one layer to be structured is disposed on
the surface of the at least one relief structure.
28. The multilayer element as claimed in claim 27, wherein, on the
first side of the carrier ply, a replicating layer is disposed and
the at least one relief structure is embossed into a surface of the
replicating layer that is remote from the carrier ply.
29. The multilayer element as claimed in claim 27, wherein the at
least one relief structure is embossed into the carrier ply.
30. The multi layer element as claimed in claim 27 wherein the at
least one relief structure is disposed at least partly in the first
region and/or in the second region.
31. The multilayer element as claimed in claim 18, wherein a
compensating layer is disposed on the side of the at least one
structured layer that is remote from the carrier ply.
32. The multilayer element as claimed in claim 28, wherein the
refractive index of the compensating layer in the visible
wavelength range is in the range from 90% to 110% of the refractive
index of the replicating layer.
33. The multilayer element as claimed in claim 31 wherein the
compensating layer is formed as an adhesion layer.
34. The multilayer element as claimed in claim 31, wherein at least
one layer of the decorative ply is disposed on the second side of
the carrier ply.
35. The multilayer element as claimed in claim 18 wherein the
decorative ply comprises at least two coating layers which evoke
different color impressions.
36. The multilayer element as claimed in claim 18, wherein the
decorative ply comprises a first coating layer, which is applied
only regionally on the carrier ply, and a second coating layer,
which is applied over the full area of the carrier ply.
37. The multilayer element as claimed in claim 18, wherein the at
least one structured layer comprises one or more of the following
layers: metal layer, HRI layer, liquid-crystal layer, polymer
layer, thin-film layer, pigment layer, semiconductor layer.
38. The multilayer element as claimed in claim 18, wherein the at
least one structured layer has a thickness in the range from 20 to
100 nm.
39. The multilayer element as claimed in claim 18, wherein the
decorative ply has a thickness in the range from 0.5 to 5
.mu.m.
40. The multilayer element as claimed in claim 19, wherein the
resist layer has a thickness in the range from 0.3 to 3 .mu.m.
41. The multilayer element as claimed in claim 18, wherein the
decorative ply comprises highly disperse pigments.
42. The multilayer element as claimed in claim 18, wherein the
decorative ply comprises nanoscaled UV absorbers based on inorganic
oxides.
43. The multilayer element as claimed in claim 18, wherein the
decorative ply comprises benzotriazole derivatives, having a mass
fraction in a range from around 3% to 5%.
44. The multilayer element as claimed in claim 18, wherein the
decorative ply comprises organic or inorganic, fluorescent pigments
in combination with highly disperse pigments.
45. The multilayer element as claimed in claim 18 wherein the
carrier ply is formed as a single-layer or multilayer carrier
film.
46. The multilayer element as claimed in claim 18, wherein a
detachment layer and/or a protective coating layer, is disposed
between the carrier ply and the at least one layer to be
structured.
Description
[0001] The invention relates to a method for producing a multilayer
element having a carrier ply and a single-layer or multilayer
decorative ply formed on and/or in the carrier ply, and also to a
multilayer element obtainable accordingly.
[0002] Optical security elements are frequently used in order to
hinder the copying of documents or products in order to prevent
their misuse. Thus optical security elements find use in securing
documents, bank notes, credit cards, money cards, identity papers,
high-value product packaging and the like. Known in these contexts
is the use of optically variable elements as optical security
elements which cannot be duplicated by conventional copying
methods. Also known is the furnishing of security elements with a
structured metal layer which is designed in the form of a text,
logo or some other pattern.
[0003] Generating a structured metal layer from a metal layer
applied two-dimensionally by sputtering or vapor deposition, for
example, requires a multiplicity of operations, particularly if the
intention is to generate fine structures which exhibit high
anticounterfeit security. Thus it is known, for example, that a
metal layer applied over the full area can be partially
demetallized and thereby structured by means of positive or
negative etching or by means of laser ablation. As an alternative
to this it is possible to apply metal layers already in structured
form to a carrier, by use of vapor deposition masks.
[0004] The greater the number of manufacturing steps in the
production of the security element, the greater the importance
accorded to the register accuracy of the individual method steps,
i.e., the accuracy in positioning of the individual tools relative
to one another during the formation of the security element, in
relation to structures or layers or features already present on the
security element.
[0005] It is an object of the present invention to specify a
multilayer element which is particularly difficult to reproduce;
and a method for producing such a multilayer element, in which a
partially shaped layer is shaped in register with another partially
shaped layer.
[0006] The object is achieved by means of a method for producing a
multilayer element, in which [0007] a) on and/or in a carrier ply
having a first side and a second side, a single-layer or multilayer
decorative ply having a first region and a second region is formed,
the decorative ply, viewed perpendicular to the plane of the
carrier ply, having in the first region a first transmittance and
in the second region a second transmittance greater in comparison
to the first transmittance, said transmittances relating to
electromagnetic radiation having a wavelength suitable for
photoactivation, [0008] b) at least one layer to be structured is
disposed on the first side of the carrier ply, [0009] c) a resist
layer which can be photoactivated by means of said electromagnetic
radiation is disposed on the first side of the carrier ply in such
a way that the resist layer is disposed on the side of the at least
one layer to be structured that is remote from the carrier ply, and
the decorative ply is disposed on the other side of the at least
one layer to be structured, [0010] d) the resist layer is exposed
from the second side of the carrier ply by means of said
electromagnetic radiation, the decorative ply serving as an
exposure mask through the design of the first region and of the
second region, and [0011] e) the at least one layer to be
structured and the resist layer are structured in register with one
another by means of structuring operations synchronized with one
another.
[0012] Steps a) to e) of the method of the invention are to be
performed preferably in the order stated. In the case of the
exposure of the photoactivatable layer by means of said
electromagnetic radiation from the side of the carrier ply that is
remote from the photoactivatable layer, through the decorative ply,
the decorative ply, which defines the first region and the second
region, acts as an exposure mask, since the first region has a
transmittance which is reduced relative to the transmittance of the
second region.
[0013] A method of this kind allows the formation of particularly
forgeryproof multilayer elements. As already mentioned, in the
method, during the production of the multilayer element, the
decorative ply serves as an exposure mask for an exposure, i.e., a
photoactivation, of the photoactivatable resist layer, and on the
completed multilayer element it serves for decoration. The
decorative ply therefore fulfills a plurality of entirely different
functions. The design of the decorative ply is more particularly
such that a viewer of an article decorated by means of the
multilayer element is able to view the at least one structured
layer through the decorative ply. The typical transmission of the
first regions of the decorative ply, therefore, is greater by at
least one order of magnitude than the typical transmission of a
conventional exposure mask, made of metal, for example. As a result
of the use of the decorative ply as an exposure mask, the resist
layer is structured in register with the first and second regions
of the decorative ply--that is, the structures of the structured
resist layer are disposed in register to the first and second
regions of the decorative ply. Furthermore, in accordance with the
method of the invention, the at least one layer to be structured is
structured in register with the resist layer. The method therefore
allows the formation of at least three layers formed in register
with one another: the decorative ply, the resist layer, and the at
least one layer to be structured. By means of the structuring step
e) the at least one layer to be structured is formed as a
structured layer. As a result of the method, the multilayer element
has the structured layer in precise register in the first region or
in the second region of the decorative ply. By register or register
accuracy is meant the positionally exact disposition of layers
lying one above another. The register fidelity or register accuracy
of the layers is monitored preferably by means of register marks or
registration marks, which are present equally on all layers and
from which, preferably by means of optical recognition methods or
sensor technology, it is readily possible to detect whether the
layers are disposed in register. Register accuracy exists in both
dimensions, i.e. length and width, of the layers.
[0014] By register is meant the precise fit on one another or over
one another of different components of the multilayer element. A
ply comprises at least one layer. A decorative ply comprises one or
more decorative and/or protective layers, formed particularly as
coating layers. The decorative layers may be disposed over the full
area or in pattern-structured form on the carrier ply. The one or
more decorative layers here may be disposed on one side or on both
sides of the carrier ply, which is formed, for example, as a base
film or carrier film. The decorative ply comprises at least one
layer which attenuates the electromagnetic radiation having the
wavelength suitable for photoactivation. In relation to the
electromagnetic radiation having the wavelength suitable for
photoactivation, the decorative ply has an optical density of
greater than zero.
[0015] As a result of the design of the exposure mask as a
decorative ply, there is automatically an absolutely 100% register
accuracy of the exposure mask relative to the decorative ply--that
is, the decorative ply itself acts at least regionally as the
exposure mask. The decorative ply and the exposure mask, then, form
a conjoint functional unit. As a result of the both simple and
effective method of the invention, the present invention affords a
considerable advantage over conventional processes in which a
separate exposure mask must be brought into register with the
decorative ply, there being very few cases in practice where
register deviations can be avoided entirely.
[0016] Through the present invention, therefore, the layer to be
structured can be structured in register with the first and second
regions, defined by the decorative layer, without additional
technological cost and complexity. In conventional processes for
generating an etch mask by means of mask exposure, with the mask
being present either as a separate unit, e.g., as a separate film
or as a separate glass plate/glass roll, or as a layer applied
subsequently by printing, the problem may arise that linear and/or
nonlinear distortions brought about by prior operating steps, more
particularly those involving thermal and/or mechanical stress, in
the multilayer element cannot be compensated completely, over the
entire area of the multilayer element, by orientation of the mask
on the multilayer element, despite mask orientation taking place on
existing register marks which are disposed preferably on the
horizontal and/or vertical edges of the multilayer element. The
tolerance here fluctuates in a comparatively large range over the
entire area of the multilayer element. With the method of the
invention, the first and second regions, defined by the decorative
layer, are utilized as a mask, with the parts of the decorative
layer that define the first and second regions being applied in an
early operating step during the production of the multilayer
element. The mask formed as a decorative layer, therefore, is
subject to all of the subsequent operating steps of the multilayer
element, and so automatically follows all of any distortions in the
multilayer element itself that may be brought about by these
operating steps. As a result, there may be no additional
tolerances, more particularly no additional tolerance fluctuations,
occurring over the area of the multilayer element, since the
subsequent generation of a mask and the associated need for
extremely register-accurate subsequent positioning of this mask,
which is independent of the course of the operation up until that
point, is avoided. The tolerances or register accuracies in the
case of the method of the invention lie only in possibly not
absolutely exactly formed edges of the first and second regions,
the quality of which is determined by the particular production
method employed. The tolerances and register accuracies in the case
of the method of the invention are situated, for instance, in the
micrometer range, and therefore well below the resolution capacity
of the eye; that is, the naked human eye is no longer able to
perceive any tolerances present.
[0017] In the case of the exposure of the resist layer from the
second side of the carrier ply, in accordance with the invention,
the resist layer is exposed to regionally different degrees. This
differing exposure of the resist layer is governed by the different
transmittances in the first and second regions of the decorative
ply, but is independent of any relief structure present, and more
particularly is independent of any relief structure impressed in
the carrier film or in a layer disposed on the carrier film. In
other words, the differing exposure of the resist layer is not
governed by a relief structure.
[0018] The structuring of the at least one layer to be structured
and of the photoactivatable resist layer, which is disposed on the
first side of the carrier ply, is determined by the different
degrees of exposure of the resist layer, which is defined in turn
by the first and second regions of the decorative ply; the
structuring, however, is independent of any relief structure that
may be present, and is not governed by a relief structure, being
independent more particularly of any relief structure impressed in
the carrier film or in a layer disposed on the carrier film. Viewed
perpendicular to the plane of the carrier ply, therefore, the
boundaries of the first and second regions of the decorative ply
correspond with register accuracy to the boundaries of the
structuring of the at least one layer to be structured and of the
photoactivatable resist layer, that are independent of and not
governed by boundaries, more particularly contours, of a relief
structure.
[0019] In accordance with step d) of the method of the invention,
the decorative ply, as a result of the design of the first region
and of the second region, serves as an exposure mask, with the
exposure mask thus formed being independent of any relief structure
that may be present, more particularly independent of any relief
structure impressed in the carrier film or in a layer disposed on
the carrier film. In accordance with step e) of the method of the
invention, the at least one layer to be structured and the resist
layer are structured in register with one another by means of
structuring operations synchronized with one another, this
structuring being dependent on the first and second regions of the
decorative ply, but independent of any relief structure that may be
present, more particularly independent of any relief structure
impressed in the carrier film or in a layer disposed on the carrier
film.
[0020] The function of the decorative ply as an exposure mask is
independent of the layer to be structured. The physical properties,
more particularly the effective thickness or the optical density,
of the layer to be structured have no influence on and are
independent of the physical properties of the decorative ply, i.e.
of the exposure mask, more particularly of the transmittances in
the first and second regions of the decorative ply. The decorative
ply, alone and detached from any relief structures present, more
particularly defractive relief structures, and from other
properties, more particularly physical and/or chemical properties,
of the layer to be structured, determines the exposure mask of the
invention. The layer to be structured is not part of the exposure
mask--that is, in the case of the present invention, the exposure
mask (i.e., decorative ply) and the layer to be structured are
present separately and are functionally decoupled.
[0021] It is possible for the at least one layer to be structured
to have a constant layer thickness over the whole area on which it
is disposed on the first side of the carrier ply.
[0022] It is possible for the decorative ply to comprise a first
coating layer which is disposed in the first region with a first
layer thickness and in the second region either not or with a
second layer thickness smaller in comparison to the first layer
thickness on the carrier ply, so that the decorative ply has said
first transmittance in the first region and said second
transmittance in the second region.
[0023] It is possible for the decorative ply to comprise a first
coloration of the carrier ply, which is formed in the first region
with a first layer thickness and in the second region either not or
with a second layer thickness smaller in comparison to the first
layer thickness, so that the decorative ply has said first
transmittance in the first region and said second transmittance in
the second region. The coloration of the carrier ply may be formed
as a colored or discolored region within the carrier ply. One
preferred method for forming a coloration of the carrier ply is a
laser marking in the carrier ply with color change, or a method in
which pigments or dyes are caused to diffuse into the carrier
ply.
[0024] One example of laser marking in the form of a blackening or
darkening of a carrier ply is the action of a laser beam on a
carrier ply made, for example, of polycarbonate (=PC), this being
particularly effective when the polycarbonate is doped. Carrier
plies of this kind are described in EP 0 991 523 B1 or EP 0 797 511
B1, for example.
[0025] One example of a method for the inward diffusion of pigments
or dyes is the printing of the carrier ply with a solventborne
color coating material, the subsequent temporal contacting of the
color coating material, and the subsequent wash removal of the
color coating material. As a result of the solvent or solvents in
the color coating material, the surface of the carrier ply material
is partly attacked, allowing parts of the color coating material to
diffuse at least into the upper carrier ply layers, situated in the
region of the attacked surface. The carrier ply material should for
this purpose be selected such that it can be attacked by a solvent
used in the color coating material. One such combination, for
example, may be a carrier ply made of polycarbonate and a color
coating material based on aromatic solvents. Following removal of
the color coating material, the inwardly diffused constituent of
the color coating material remains in the carrier ply. Depending on
the layer thickness of the applied color coating material and on
the selection of the carrier ply material, different amounts of
pigments or dyes may diffuse to different depths into the carrier
ply. The inward diffusion does produce a slight lack of definition
at the margins of the first and/or second regions but the
horizontal extent of this lack of definition lies only in the
region of the preferably vertical layer thickness of the printed-on
color coating material. In this context, "vertical" refers to an
extent substantially perpendicular to the carrier ply, and
"horizontal" to an extent substantially in the plane formed by the
carrier ply. If, for example, a color coating layer of a few
micrometers, e.g., 1 to 10 .mu.m is applied by printing in a
printing process, the lack of definition also lies only in this
region from 1 to 10 .mu.m, and hence well below the resolution
capacity of the eye.
[0026] Another example of a method for the inward diffusion of
pigments or dyes is the regional printing of a carrier ply with a
liftoff coating material for masking the second regions. The
carrier ply is subsequently exposed to an atmosphere containing a
vaporized colorant, such as, for example, an atmosphere comprising
an inert gas such as argon or nitrogen and vaporized iodine. In the
first regions, not covered by the liftoff coating material, the
vaporized colorant then diffuses into the carrier ply. The liftoff
coating material can be subsequently removed. Alternatively, or
else in combination with this, the carrier ply printed regionally
with the liftoff coating material may travel through a bath,
containing, for example, apolar solvents such as toluene or
benzine, and a dye dissolved therein, and preferably a UV blocker
(UV=ultraviolet) likewise in solution in the bath. In this case,
the liftoff coating material must be resistant to the solvents of
the bath, in the form of a water-soluble liftoff coating material,
for example. The dye and, where appropriate, the UV blocker diffuse
into the first carrier ply regions, not covered by the liftoff
coating material, in the bath, and thereby color the carrier ply.
The liftoff coating material can be subsequently removed from the
carrier ply.
[0027] Another example of a method for the inward diffusion of
pigments or dyes is the printing of the carrier ply by means of a
thermal sublimation process, in which dye is sublimed, i.e.,
evaporated, from a separate color carrier ply by means of local
heat exposure through a thermal printing head. This color vapor is
then able to diffuse into the carrier ply, with the possibility of
obtaining high resolutions of around 300 dpi (=dots per inch). In
order to increase further the edge definition on inward diffusion,
it is possible to use an additional mask, which is disposed between
thermal printing head and carrier ply and which masks regions of
the carrier ply that are not to be colored.
[0028] It is possible for a layer of the decorative ply to be
formed regionally in different layer thicknesses on and/or within
the carrier ply. It is possible for a layer of the decorative ply
to be formed as a layer having substantially uniform thickness, and
for the layer to be formed only regionally, i.e., in
pattern-structured form, on and/or within the carrier ply. In this
context it is possible for the decorative ply to comprise layers
applied only on one side of the carrier ply, or layers applied on
both sides of the carrier ply.
[0029] The object is further achieved by means of a multilayer
element having a carrier ply which has a first side and a second
side, and a single-layer or multilayer decorative ply formed on
and/or in the carrier ply, the decorative ply having a first region
and a second region and, viewed perpendicular to the plane of the
carrier ply, having in the first region a first transmittance and
in the second region a second transmittance greater in comparison
to the first transmittance, said transmittances relating to
electromagnetic radiation having a wavelength suitable for
photoactivation, the multilayer element also having at least one
layer which is structured in register to the first region and the
second region.
[0030] The multilayer element of the invention can be used, in the
form of a label, laminating film, hot-stamping film or transfer
film, for example, for the provision of an optical security element
which is employed for securing documents, bank notes, credit cards,
money cards, identity papers, high-value product packaging and the
like. Here, the decorative ply and the at least one structured
layer disposed in register therewith may serve as an optical
security element.
[0031] Where, below, a disposition of an article in the first
region and/or in the second region is described, this should be
taken to mean that the article is disposed such that the article
and the first and/or second region(s) of the decorative ply
overlap, as viewed perpendicular to the plane of the carrier ply.
Also, below, the terms "first region" and "second region", on the
basis of the decorative ply, are also transposed to other articles,
e.g. layers/plies of the multilayer element. A first/second region
of an article means that the first/second region of the decorative
ply and the first/second region of the article are congruent, as
viewed perpendicular to the plane of the carrier ply.
[0032] The exposure mask formed by the decorative ply comprises the
first region and the second region, which have different
transmittances in relation to the radiation used for the exposure.
The exposure mask therefore does not have a region which is
absolutely opaque to the radiation used for the exposure, but
instead only a region having a higher transmittance and a region
having a lower transmittance, and may therefore be referred to as a
halftone mask. The region of the photoactivatable layer that is
exposed through the first region is activated to a lower degree
than the region of the photoactivatable layer that is exposed
through the second region, since the first region possesses a lower
transmittance than the second region.
[0033] It has been found appropriate if the photoactivatable layer
is formed using a positive photoresist, whose solubility increases
on activation by exposure, or a negative photoresist, whose
solubility decreases on activation by exposure. Exposure is the
term for the selective irradiation of a photoactivatable layer
through an exposure mask with the aim of producing local changes in
the solubility of the photoactivatable layer as a result of a
photochemical reaction. According to the nature of the change in
solubility that is achievable photochemically, a distinction is
made between the following photoactivatable layers, which may be
designed as photoresists: in the case of a first type of
photoactivatable layers (e.g., negative resist), their solubility
decreases by exposure in comparison to unexposed regions of the
layer, because, for example, the light leads to hardening of the
layer; in the case of a second type of photoactivatable layer (e.g.
positive resist), their solubility increases by exposure in
comparison to unexposed regions of the layer, because, for example,
the light leads to the decomposition of the layer.
[0034] It has been found appropriate, furthermore, if the resist
layer is removed in the second region, when using a positive
photoresist, or in the first region, when using a negative
photoresist. This can be accomplished by means of a solvent such as
an alkali or acid. When a positive photoresist is used, the more
highly exposed second region of the resist layer has a higher
solubility than the less exposed first region of the resist layer.
Consequently, a solvent dissolves the material of the resist layer,
i.e., the positive photoresist disposed in the second region, more
rapidly and more effectively than the material of the resist layer
disposed in the first region. Through the use of a solvent,
therefore, it is possible to structure the resist layer--that is,
the resist layer is removed in the second region, but remains
intact in the first region.
[0035] It has been found appropriate if the layer to be structured
is removed in the first or second regions in which the resist layer
has been removed. This can be accomplished by means of an etchant
such as an acid or alkali. It is preferred if the regional removal
of the resist layer in the first or second region and of the
regions thereby laid bare in the first or second region, of the
layer to be structured, are accomplished in the same method step.
This can be achieved in a simple way by means of a solvent/etchant
such as an alkali or acid which is capable of removing not only the
resist layer--in the exposed region in the case of a positive
resist or in the unexposed region in the case of a negative
resist--but also the layer to be structured--i.e., which attacks
both materials. In this case the resist layer must be of a form
such that it withstands the solvent or etchant used for removing
the layer to be structured, in the unexposed region when using a
positive resist and in the exposed region when using a negative
resist, for at least a sufficient time, i.e., for the solvent or
etchant contact time.
[0036] One preferred embodiment envisages the removal of the resist
during the workstep for removing the layer to be structured, in the
first or second region, or in a separate, subsequent, later
workstep, this removal being likewise largely complete (and known
as "stripping"). In this case, by reducing the number of layers
situated one above another in the multilayer element, it is
possible to increase the robustness and durability of said element,
since adhesion problems between adjacent layers are minimized.
Moreover, the optical appearance of the multilayer element can be
improved, since, following removal of the resist, which in
particular may be colored and/or not completely transparent, but
instead only translucent or opaque, the underlying regions lie free
again. For specific applications without particularly exacting
requirements in terms of the robustness or the optical appearance,
however, it is also possible to leave the resist on the structured
layer. Leaving the resist on the structured layer may be
advantageous particularly when it is configured as a relatively
stable negative resist and has been colored. For this purpose the
resist may also be printed with two or more colors. Accordingly,
different color impressions are produced when the multilayer
element is viewed from different sides.
[0037] It is preferred if the resist layer is exposed from the side
of the carrier ply remote from the resist layer, by means of said
electromagnetic radiation, with the decorative ply, as a result of
the design of the at least one first region and of the at least one
second region, serving as an exposure mask. The at least one layer
to be structured is structured in register with the at least one
first region and with the at least one second region, by means of
the photoactivatable layer removed in the at least one first region
or the at least one second region after the exposing.
[0038] It is preferred if the resist layer comprises a
UV-activatable material. In this case UV radiation can be used for
exposure step d). As a result, the visual properties of the
multilayer element can be separated from the desired operational
properties for the structuring of the at least one layer to be
structured. Exposure step d) is designed such that the radiation
completely penetrates the resist layer, in other words reaching
through to its outer surface, remote from the carrier ply. Only
then is it readily possible to use a solvent to remove the resist
from the side of the outer surface of the resist layer. If the
resist is not irradiated through completely, it generally still has
a "skin" on its outer surface, remote from the carrier ply, which
at least partly prevents the attack of a solvent.
[0039] The carrier ply must be transparent to the radiation used in
exposure step d). For exposure it has been found appropriate to use
electromagnetic radiation having a radiation maximum in the region
of 365 nm, since in this region PET (polyethylene terephthalate),
which may form a substantial constituent of the carrier ply, is
transparent. In the region of this wavelength is located the
maximum of the emission of a high-pressure mercury lamp. In the
case of the following carrier materials it is also possible to use
electromagnetic radiation having a wavelength in the range from 254
to 314 nm: olefinic carrier material such as PP (polypropylene) or
PE (polyethylene), PVC-based and PVC copolymer-based carrier
material, carrier material based on polyvinyl alcohol and polyvinyl
acetate, and polyester carriers based on aliphatic raw
materials.
[0040] It has emerged as being advantageous to select the thickness
and the material of the decorative ply in such a way that the first
transmittance is greater than zero. The thickness and the material
of the decorative ply are selected such that electromagnetic
radiation having the wavelength suitable for photoactivation partly
penetrates the decorative ply in the first region. Accordingly, the
exposure mask formed by the decorative ply is radiation-transparent
in the first region.
[0041] It has been found appropriate for the thickness and the
material of the decorative ply to be selected such that the ratio
between the second and first transmittances is greater than or
equal to two. The ratio between the first and second transmittances
is preferably 1:2, also referred to as contrast 1:2. A contrast of
1:2 is smaller by at least one order of magnitude than for
conventional masks. Hitherto it was not customary to use a mask
with such a low contrast like the decorative ply described here for
exposing a resist layer. In the exposure of a resist using a
conventional mask (e.g. a chromium mask), there are opaque regions,
i.e., regions with OD>2, and completely transparent regions; the
mask, therefore, exhibits a high contrast. A conventional aluminum
mask has a typical contrast of 1:100, since the typical
transmittance of an aluminum layer is located at values around 1%,
corresponding to an optical density (OD) of 2.0. The transmittance
(T) and the OD are linked to one another as follows: t=10.sup.-OD
(i.e. OD=0 corresponds to T=100%; OD=2 corresponds to T=1%; OD=3
corresponds to T=0.1%). In contrast to conventional exposure
processes, in the case of the present invention the resist layer is
exposed not only through a low-contrast mask (i.e., decorative ply)
but also through the layer to be structured.
[0042] It is additionally possible for at least one functional
layer, more particularly a detachment layer and/or a protective
coating layer, to be disposed between the carrier ply and the at
least one layer to be structured, preferably directly on the first
side of the carrier ply. This is advantageous particularly when
using the multilayer film as a transfer film, where the functional
layer enables trouble-free detachment of the carrier ply from a
transfer ply comprising at least one layer of the decorative ply
and the structured layer.
[0043] It has been found appropriate for the thickness and the
material of the decorative ply to be selected such that the
electromagnetic radiation, measured after one pass through a layer
stack consisting of the carrier ply, the at least one functional
layer, and the decorative ply, has a transmittance of around 0.3 in
the first region and a transmittance of around 0.7 in the second
region. A contrast of this kind between the two regions designed as
different transmission regions, i.e., the first region and the
second region, is sufficient particularly in the case of a positive
resist layer.
[0044] It is possible for at least one relief structure to be
formed on the first side of the carrier ply and for the at least
one layer to be structured to be disposed on the surface of the at
least one relief structure. For this purpose, consideration may be
given to disposing a replicating layer on the first side of the
carrier ply and embossing the at least one relief structure into a
surface of the replicating layer that is remote from the carrier
ply. Consideration may also be given, however, to embossing the at
least one relief structure directly into the carrier ply. In that
case the carrier ply must have a replicatable carrier material
suitable for a replicating process on the first side of the carrier
ply, an example of such material being PVC (polyvinyl chloride),
PC, PS (polystyrene) or PVA (polyvinyl acetate). A replicating
layer, generally speaking, is a layer which can be produced
superficially with a relief structure. The term includes, for
example, organic layers such as polymeric layers or coating layers,
or inorganic layers such as inorganic plastics (e.g., silicones),
glass layers, semiconductor layers, metal layers, and so on, and
also combinations thereof. It is preferred for the replicating
layer to be formed as a replicating coating layer. To form the
relief structure, a radiation-curable replicating layer can be
applied to the carrier ply, a relief impressed into the replicating
layer, and the replicating layer cured with the relief embossed
therein. It is preferred if the relief is formed as a
light-diffracting or light-refracting or light-scattering,
microscopic or macroscopic structure, such as a diffractive
structure or a diffraction grating or a matt structure, or
combinations of light-diffracting or light-refracting or
light-scattering, microscopic or macroscopic structures, such as
diffractive structures, matt structures or diffraction
gratings.
[0045] It is possible for the at least one relief structure to be
disposed at least partly in the first region and/or in the second
region. The area layout of the relief structure in this case may be
adapted to the area layout of the first and second regions, and
more particularly may be designed in register therewith, or, for
example, the area layout of the relief structure is formed as a
continuous, infinite pattern independently of the area layout of
the first and second regions. As a result of the inventive
disposition of the resist layer on the first side of the carrier
ply in such a way that the resist layer is disposed on the side of
the at least one layer to be structured that is remote from the
carrier ply and the decorative ply is disposed on the other side of
the at least one layer to be structured, it is possible for the
layer to be structured to be disposed at least partly on a relief
structure, in contrast to structuring processes using washcoat
material. In a conventional structuring process using washcoat
material comprising silica (silicon dioxide) or titanium dioxide
(e.g., rutile), the silica and the titanium dioxide act
destructively, by mechanical exposure, on the surface of the
replicating roll, especially with a nickel surface.
[0046] Furthermore, the differences in level between the washcoat
layer and the underlying layer into which the relief structure is
to be embossed are also a hindrance to replication.
[0047] It is possible for a compensating layer to be applied on the
first side of the carrier ply after step e). The structuring step
e) forms the layer to be structured as a structured layer. It is
preferred if after step e) the structured layer and the resist
layer is removed in the first or second region and present in the
other region. Through application of the compensating layer it is
possible for indented regions/indentations of the structured layer
to be at least partly filled. Through application of the
compensating layer it is possible as well for indented
regions/indentations of the resist layer to be at least partly
filled. The compensating layer may comprise one or more different
layer materials. The compensating layer may be designed as a
protective and/or adhesive and/or decorative layer. It is possible
for an adhesion promoting layer, e.g., adhesive layer, to be
applied to the side of the compensating layer that is remote from
the carrier ply. Accordingly, the multilayer element in the form of
a laminating film or transfer film can be joined to a substrate
adjoining the adhesion promoting layer, in--for example--a
hot-stamping or IMD process (IMD=In-Mold Decoration). The substrate
may be, for example, paper, card, textile or another fiber
material, or a plastic, and may be flexible or predominantly
rigid.
[0048] It is possible for at least one layer of the decorative ply
to be applied on the second side of the carrier ply. By this means
it is possible for one or more layers of the at least one layer to
be removed again after the exposure step, in which the decorative
ply serves as an exposure mask. It is therefore possible for one or
more layers of the at least one layer of the decorative ply that is
applied on the second side of the carrier ply to be removed from
the carrier ply again after exposure step d).
[0049] It is preferred if the decorative ply is at least partly
transparent to visible light having a wavelength in a range from
approximately 380 to 750 nm. It is possible, if the decorative ply
is colored with at least one opaque and/or at least one transparent
colorant which at least in one wavelength range of the
electromagnetic spectrum is colored or color-generating, more
particularly is chromatically colored or chromatically
color-generating, more particularly if the decorative ply comprises
a colorant which can be excited outside the visible spectrum and
generates a visually perceptible colored impression. It is possible
for the decorative ply to be colored with at least one pigment or
at least one colorant of the color cyan, magenta, yellow or black
(CMYK=Cyan Magenta Yellow Key; key: black as depth of color) or of
the color Red, Green or Blue (RGB), more particularly for the
purpose of generating a subtractive mix color, and/or to be
provided with at least one red and/or green and/or blue
fluorescent, radiation-excitable pigment or dye and thereby, more
particularly for an additive mix color to be generated on
irradiation. This coloring may be largely constant over the entire
colored area region or else to be formed as a color profile which
more particularly is continuous, an example being a linear or
radial color profile, in other words for the coloration to have a
gradient, it being possible for the coloration to vary more
particularly between two or more hues, for example, from red to
blue and further to green, or between one or more hues and an
achromatic, for example, between red and transparent, i.e., an
uncolored decorative ply. Color profiles of these kinds are known
and widespread in security printing because it is difficult for
them to be counterfeited.
[0050] As a result, the decorative ply performs a dual function. On
the one hand, the decorative ply acts as an exposure mask for
forming at least one structured layer which is disposed in register
with the first and second regions of the decorative ply. The
decorative ply serves more particularly as an exposure mask for a
regional demetallization of a metal layer. On the other hand the
decorative ply, or at least one or more layers of the decorative
ply, on the multilayer element serves as an optical component, more
particularly as a single-color or multicolor color layer for a
coloration of the at least one structured layer, in which case the
color layer is disposed in register above and/or next to/adjacent
to the at least one structured layer.
[0051] It is possible for the multilayer element in the first
region or the second region to have a resist layer which can be
photoactivated by means of said electromagnetic radiation, in which
case the at least one structured layer and the resist layer are
disposed in orientation with one another on the first side of the
carrier ply in such a way that the resist layer is disposed on the
side of the at least one structured layer that is remote from the
carrier ply, and the decorative ply is disposed on the other side
of the at least one structured layer.
[0052] It is possible for the decorative ply to comprise a first
coating layer, which is disposed in the first region with a first
layer thickness and in the second region either not or with a
second layer thickness smaller in comparison to the first layer
thickness, on the carrier ply, so that the decorative ply has said
first transmittance in the first region and said second
transmittance in the second region.
[0053] It is possible for the decorative ply to comprise a first
coloration of the carrier ply which is formed in the first region
with a first layer thickness and in the second region either not or
with a second layer thickness smaller in comparison to the first
layer thickness, so that the decorative ply has said first
transmittance in the first region and said second transmittance in
the second region.
[0054] It is preferred if the ratio between the second
transmittance and the first transmittance is greater than two.
[0055] It is possible for at least one relief structure to be
formed on the first side of the carrier ply and for the at least
one layer to be structured to be disposed on the surface of the
least one relief structure. In that case it is possible for a
replicating layer to be disposed on the first side of the carrier
ply and for the at least one relief structure to be embossed into a
surface of the replicating layer that is remote from the carrier
ply. It is also possible, however, for the at least one relief
structure to be embossed into the carrier ply. It is possible for
the relief structure to be formed as a diffractive relief
structure. It is preferred if the at least at least one relief
structure is disposed at least partly in the first region and/or in
the second region.
[0056] It is possible for a compensating layer to be disposed on
the side of the at least one structured layer that is remote from
the carrier ply. It is preferred if the refractive index n1 of the
compensating layer in the visible wavelength range is situated in
the range from 90% to 110% of the refractive index n2 of the
replicating layer. It is preferred if in the first or second
regions in which the structured layer is removed and a
three-dimensional structure, i.e. a relief, is formed on the
surface, the indentations and elevations of the relief are evened
out by means of a compensating layer which has a refractive index
similar to that of the replicating layer, i.e.,
.DELTA.n=|n2-n1|<0.3. In this way the optical effect formed by
the relief is no longer perceptible in the regions in which the
compensating layer is applied directly to the replicating
layer.
[0057] It is possible for the compensating layer to be formed as an
adhesion layer, e.g., adhesive layer. It is possible for at least
one layer of the decorative ply to be disposed on the second side
of the carrier ply. It is possible for the decorative ply to
comprise at least two coating layers which evoke different color
impressions. It is possible for the decorative ply to comprise a
first coating layer, which is applied only regionally on the
carrier ply, and a second coating layer which is applied over the
full area of the carrier ply.
[0058] It is possible for the at least one structured layer to
comprise one or more of the following layers: metal layer, more
particularly comprising copper, aluminum, silver and/or gold, HRI
layer (HRI=High Refractive Index), more particularly comprising ZnS
or TiO.sub.2, liquid-crystal layer, polymer layer, more
particularly conductive or semiconducting polymer layer, thin-film
interference layer stack, pigment layer, semiconductor layer. The
at least one structured layer is not confined to the exemplary
embodiments stated. The layer to be structured may be any material
which can be attacked, i.e., dissolved or removed, by a solvent or
etchant. It is possible for the at least one structured layer to
have a thickness in the range from 20 to 1000 nm, more particularly
20 to 100 nm. It is preferred that the structured layer of the
multilayer element as a reflection layer for light incident from
the side of the replicating layer. Through the combination of a
relief structure of the replicating layer and a structured layer
disposed beneath it, formed for example as a metal layer, it is
possible to generate a multiplicity of different optical effects
which can be used actively for security aspects. The structured
layer may be made of metal, as for example aluminum or copper or
silver, which in a subsequent method step is galvanically
reinforced. The metal used for the galvanic reinforcement may be
the same as or different from the metal of the structured layer.
One example is the galvanic reinforcement of a thin silver layer
with copper, for example.
[0059] It is possible for the resist layer to have a thickness in
the range from 0.3 to 3 .mu.m. It has been found appropriate if the
resist layer is designed as an etch resist, in which case the
resist layer, if it is designed as a positive photoresist, has a
high resistance in the unexposed region and, if it is designed as a
negative photoresist, has a high resistance in the exposed region,
to an etchant which attacks the layer to be structured, this
resistance being sufficient to prevent the access of the etchant to
the layer to be structured, in the region covered by the resist
layer, substantially, at least until the etchant has removed the
layer to be structured in the desired region. Said desired region,
if the resist layer is designed as a positive photoresist, is the
exposed region, and, if the resist layer is designed as a negative
photoresist, is the unexposed region.
[0060] It is possible for the decorative ply to have a thickness in
the range from 0.5 to 5 .mu.m. It is possible for the decorative
ply to comprise dyes or highly disperse pigments, more particularly
a Mikrolith.RTM. K pigment dispersion. This is advantageous
particularly in the case of a colored decorative ply with pigment
fraction. It is possible for UV absorbers to be added to the
material forming the decorative ply, especially if said material
comprises relatively few pigments or other UV-absorbing
constituents. It is possible for the decorative ply to comprise
inorganic absorbers having a high scatter fraction, more
particularly nanoscaled UV absorbers based on inorganic oxides.
Oxides which have proven suitable are, in particular, TiO.sub.2 and
Zno in highly disperse form, of the kind also used in sun
protection creams with a high light protection factor. These
inorganic absorbers lead to high scattering and are therefore
suitable especially for a matt coloration, more particularly a
satin-matt coloration, of the decorative ply. It is possible for
the decorative ply to comprise organic absorbers, more particularly
benzotriazole derivatives, having a mass fraction in the range from
around 3% to 5%. Suitable organic absorbers are sold under the
trade name Tinuvin.RTM. by the company Ciba, Basle, Switzerland. It
is possible for the decorative ply to comprise fluorescent dyes or
organic or inorganic, fluorescent pigments in combination with
highly disperse pigments, more particularly Mikrolith.RTM. K. As a
result of the excitation of these fluorescent pigments, the UV
radiation is very largely filtered out by the decorative ply
itself, with the consequence that only an insignificant fraction of
the radiation reaches the resist layer. The fluorescent pigments
may be used in the multilayer element as an additional security
feature.
[0061] The use of a UV-activatable resist layer offers advantages:
Through the use of a UV absorber which is transparent in the visual
wavelength range, in the decorative ply the "color" property of the
decorative ply in the visual wavelength range may be separated from
desired properties of the decorative ply for the structuring of the
resist layer, e.g., sensitive in near-UV, and hence of the at least
one layer to be structured. In this way, a high contrast can be
achieved between the first and second regions, independently of the
visually perceptible coloration of the decorative ply.
[0062] It is possible for the carrier ply to be formed as a
single-layer or multilayer carrier film. A carrier film thickness
for the multilayer element of the invention in the range from 12 to
100 .mu.m has been found appropriate. An example of material
contemplated for the carrier film includes PET, but also other
polymeric materials, such as PEN (polyethylene naphthalate) or PMMA
(polymethyl methacrylate). It is possible for one or more
functional layers, more particularly a detachment layer and/or a
protective coating layer, to be disposed directly on the first side
of the carrier ply.
[0063] The invention is elucidated by way of example by the
drawings, in which
[0064] FIG. 1a shows a schematic section through a first
manufacturing stage of the multilayer element shown in FIG. 8a;
[0065] FIGS. 1b-c show schematic sections through two alternative
embodiments of a first manufacturing stage;
[0066] FIG. 1d shows a schematic plan view of the first
manufacturing stage shown in FIG. 1a;
[0067] FIG. 2 shows a schematic section through a second
manufacturing stage of the multilayer element shown in FIG. 8a;
[0068] FIG. 2a shows a schematic section through an alternative
embodiment of a second manufacturing stage;
[0069] FIG. 3 shows a schematic section through a third
manufacturing stage of the multilayer element shown in FIG. 8a;
[0070] FIG. 4 shows a schematic section through a fourth
manufacturing stage of the multilayer element shown in FIG. 8a;
[0071] FIG. 5 shows a schematic section through a fifth
manufacturing stage of the multilayer element shown in FIG. 8a;
[0072] FIG. 6 shows a schematic section through a sixth
manufacturing stage of the multilayer element shown in FIG. 8a;
[0073] FIG. 7 shows a schematic section through a seventh
manufacturing stage of the multilayer element shown in FIG. 8a;
[0074] FIG. 7a shows a schematic section through an eighth
manufacturing stage of the multilayer element shown in FIG. 8a;
[0075] FIG. 8a shows a schematic section through a first exemplary
embodiment of an inventive multilayer element, formed using a
positive resist;
[0076] FIG. 8b shows a schematic section through an alternative
exemplary embodiment of a multilayer element of the invention;
[0077] FIG. 9 shows a schematic section through a further exemplary
embodiment of an inventive multilayer element, formed using a
negative resist;
[0078] FIG. 10 shows a schematic section through a further
exemplary embodiment of a multilayer element of the invention;
[0079] FIGS. 11a-g show schematic representations of possible
designs of the decorative ply;
[0080] FIG. 12 shows a schematic section through a further
exemplary embodiment of a multilayer element of the invention;
[0081] FIG. 13 shows a schematic section through a manufacturing
stage of a multilayer element;
[0082] FIG. 14 shows a schematic section through a further
manufacturing stage of a multilayer element; and
[0083] FIG. 15 shows transmission spectra of different UV
absorbers.
[0084] FIGS. 1a to 14 are drawn each schematically and not to
scale, in order to ensure a clear representation of the key
features.
[0085] FIG. 8a shows a multilayer element 100, which comprises a
carrier ply 1 having a first side 11 and a second side 12, a
functional layer 2 disposed on the first side 11 of the carrier ply
1, a decorative ply 3 disposed on the functional layer 2 and having
a first coating layer 31 formed in a first region 8, a replicating
layer 4 adjoining the decorative layer 3, a structured layer 5
disposed on the replicating layer 4 and in register with the first
coating layer 3, and compensating layer 10 disposed on the
replicating layer 4 and the structured layer 5.
[0086] The carrier ply 1 comprises a preferably transparent
polymeric film with a thickness of between 8 .mu.m and 125 .mu.m,
preferably in the range from 12 to 50 .mu.m, more preferably in the
range from 16 to 23 .mu.m. The carrier film 1 may be formed as a
mechanically and thermally stable film made of a translucent
material, e.g. of ABS (acrylonitrile-butadiene-styrene), BOPP
(biaxially oriented polypropylene), PEN or PC, but preferably of
PET. This carrier film 1 may be monoaxially or biaxially oriented.
Furthermore, it is also possible for the carrier film 1 to consist
not of just one layer but instead of two or more layers. Thus it is
possible, for example, for the carrier film 1 to have a detachment
layer as well as a polymeric carrier, for example, a polymeric film
as described above, said detachment layer allowing the detachment
of the layer structure consisting of the layers 2 to 6 and 10 from
the polymeric film, as for example when the multilayer element 100
is used as a hot-stamping foil.
[0087] The functional layer 2 may comprise a detachment layer, made
of hot-melting material, for example, which facilitates detachment
of the carrier film 1 from the layers of the multilayer element 100
which are disposed on a side of the detachment layer 2 that is
remote from the carrier film 1. This is especially advantageous if
the multilayer element 100 is designed as a transfer ply, as
employed, for example, in a hot-stamping process or an IMD process.
It has been found appropriate, moreover, especially if the
multilayer element 100 is used as a transfer film, for the
functional layer 2 to have a protective layer, e.g., a protective
coating layer, as well as a detachment layer. After the multilayer
element 100 has been joined to a substrate and after the transfer
film 1 has been detached from the layers of the multilayer element
100 which are disposed on a side of the detachment layer 2 that is
remote from the carrier film 1, the protective layer forms one of
the upper layers of the layers disposed on the surface of the
substrate, and is able to protect underlying layers from abrasion,
damage, chemical attacks or the like. The multilayer element 100
may be a section of a transfer film, as for example of a
hot-stamping foil, which can be disposed on a substrate by means of
an adhesive layer. The adhesive layer is preferably disposed on the
side of the compensating layer 10 that is remote from the carrier
film 1. The adhesive layer may be a hotmelt adhesive, which melts
on thermal exposure and joins the multilayer element 100 to the
surface of the substrate.
[0088] When the multilayer element 100 is formed as a laminating
film, i.e., without a detachment layer for detaching the carrier
film 1 from the layers of the multilayer element 100, it is
possible, additionally or alternatively to the adhesive layer, for
a further carrier film to be provided on the side of the
compensating layer 10 that is remote from the carrier film 1. This
laminate element, consisting of two outside carrier films and the
inside layers of the multilayer element 100, may be used further by
being laminated into card assemblies, for example, made of PC, for
example. For this purpose it is advantageous if the carrier films
are made of the same material as the card assembly layers that
adjoin the laminate element--for example, likewise made of PC.
[0089] On the functional layer 2, in the region 8, a transparent,
colored coating layer 31 is printed. Transparent means that the
coating layer 31 is at least partly pervious to radiation in the
visible wavelength range. Colored means that the coating layer 31
exhibits a visible color impression when there is sufficient
daylight.
[0090] Not only the regions 8 printed with the coating layer 31 but
also the unprinted regions 9 of the functional layer 2 are covered
by a replicating layer 4 which evens out the relief structure of
the decorative ply 3, i.e., the differing levels in the printed
regions 8 and unprinted regions 9. In a second zone, zone 42, the
replicating layer 4 has a relief structure which is not present in
a first zone, zone 41. Disposed on the replicating layer 4, in
register and congruent with the coating layer 31 when viewed
perpendicular to the plane of the carrier ply 1, is a thin metal
layer 5. Not only the regions 8 of the replicating layer 4 that are
covered with the metal layer 5 but also the uncovered regions 9 of
the replicating layer 4 are covered with a compensating layer 10,
which evens out the structures (e.g., relief structure 42,
different layer thicknesses, height offset) brought about by the
relief structure 42 and by the regionally 8 disposed metal layer
5--that is, it covers and fills them, so that the multilayer
element, on the side of the compensating layer 10 that is remote
from the carrier film 1, has a planar, substantially structureless
surface. Where the refractive index of the compensating layer 10 is
similar to that of the replicating layer 4, i.e., the refractive
index difference is less than about 0.3, those regions of the
relief structure 42 that directly adjoin the compensating layer 10
and are not covered by the metal layer 5 are optically extinguished
in the replicating layer 4, since there, on account of the similar
refractive index of the two layers, there are no longer any
optically detectable layer boundaries between the replicating layer
4 and the compensating layer 10.
[0091] FIGS. 1a to 7a now show manufacturing stages of the
multilayer element 100 shown in FIG. 8a. Components identical to
those in FIG. 8a are given the same reference numerals.
[0092] FIG. 1a shows a first manufacturing stage 100a of the
multilayer element 100, in which a functional layer 2 and a
decorative ply 3 are disposed on a first side 11 of a carrier film
1. One side of the functional layer 2 adjoins the carrier film 1;
its other side adjoins the decorative ply 3. The decorative ply 3
has a first region 8, in which a coating layer 31 is formed, and a
second region 9, in which the coating layer 31 is absent. The
coating layer 31 is printed on the functional layer 2, by screen,
gravure or offset printing, for example. As a result of the
regional formation--that is, the formation confined to the first
region 8--of the coating layer 31, the decorative ply 3 is given a
patterned design.
[0093] FIG. 1d shows a plan view of the first manufacturing stage
100a, shown in FIG. 1a, of the multilayer element 100, with a
viewing direction perpendicular to the plane of the carrier film 1.
Printed on the functional layer 2, disposed over the full area of
the carrier film 1, in the first region 8 is the coating layer 31,
while the second region, region 9, of the functional layer 2 is not
printed with the coating layer 31, i.e., is left bare. In the
exemplary embodiment shown in FIG. 1b, the first region 8 consists
of two rectangular areas. As well as geometric patterns of this
kind, the first region 8, provided with the coating layer 31, may
have any desired form, examples being alphanumeric characters,
symbols, logos, fine-line patterns, e.g., grids, or ornaments,
e.g., guilloches, or geometrical, pictorial or figurative patterns.
In FIG. 1b, a sectional plane Ia is indicated; when the sectional
plane Ia is viewed in the viewing direction indicated by the arrow,
the section shown in FIG. 1a is produced.
[0094] FIG. 1b shows an alternative design of a first manufacturing
stage of an inventive multilayer element. In contrast to the
exemplary embodiment shown in FIG. 1a, the decorative ply 3 in the
exemplary embodiment shown in FIG. 1b is formed not on the carrier
film 1 but instead in the carrier film 1. The carrier film 1
consists of three layers, 1a, 1b, and 1c. The two outer layers, 1a
and 1c, consist of PC. The in-between, middle layer, layer 1b,
consists of a polymeric material, e.g., an additized PC, which on
exposure to laser radiation of a particular energy exhibits a color
change from a transparent, colorless, first state to a transparent,
colored, second state--i.e., what is called laser blackening. The
polymeric material remains in the second state, once it has been
achieved, even after the laser radiation has been removed. This
means that the carrier film 1 is both decorative ply and
carrier.
[0095] FIG. 1c shows another alternative design of a first
manufacturing stage of an inventive multilayer element. As in the
case of the exemplary embodiment shown in FIG. 1b, the decorative
ply 3 in the exemplary embodiment shown in FIG. 1c is also formed
not on the carrier film 1 but instead in the carrier film 1. The
carrier film 1 consists of a polymeric material into which
dye/color pigments are able to diffuse. For forming the decorative
ply 3, the second surface 12 of the carrier film 1 has been
contacted in the first region 8 for a particular time period with a
substance from which, color pigments are able to diffuse into the
carrier film 1. During this time period, a part of these color
pigments diffused into the carrier film 1, and so the colored
regions 34 were formed with a particular layer thickness. This
means that the carrier film 1 is both decorative ply and
carrier.
[0096] FIG. 2 shows a second manufacturing stage 100b of the
multilayer element 100 formed from the first manufacturing stage
100a in FIG. 1a by application of a replicating layer 4 to the
functional layer 2 and to the coating layer 31 disposed thereon
regionally, i.e., in such a way as to be confined to the first
region 8. Said layer 4 may be an organic layer which is applied by
conventional coating techniques, such as printing, pouring or
spraying, in liquid form. Here, the replicating layer 4 is applied
over the full area. The thickness of the replicating layer 4 varies
since it compensates/evens out the different levels of the
decorative ply 3, comprising the printed, first region and the
unprinted, second region 9; in the first region 8, the thickness of
the replicating layer 4 is thinner than in the second region 9, and
so the side of the replicating layer 4 that is remote from the
carrier ply 1 has a planar, substantially structureless surface
before the relief structure is formed in the second zone 42. It is,
however, also possible for the replicating layer 4 to be applied
only in a subregion of the multilayer element 100. The surface of
the replicating layer 4 is structured in a second zone 42, by known
methods, whereas it is unstructured in a first zone 41. For this
purpose, for example, as replicating layer 4, a thermoplastic
replicating coating material is applied by printing, spraying or
painting, and a relief structure is impressed in the second zone 42
into the replicating coating material 4, which can be dried/cured
thermally in particular, by means of a heated die or a heated
replicating roller. The replicating layer 4 may also be a
UV-curable replicating coating material, which is structured, for
example, by a replicating roller and then cured by means of UV
radiation. The structuring may alternatively be brought about by UV
radiation through an exposure mask. In this way the second zone 42
may be impressed into the replicating layer 4.
[0097] FIG. 2a shows an alternative second manufacturing stage of a
multilayer element formed from the first manufacturing stage shown
in FIG. 1b by the embossing of a relief structure 42 into the first
side 11 of the carrier film 1. This means that the carrier film 1
is decorative ply, carrier and replicating layer all at the same
time. Of course there are also alternatives possible in which only
one relief structure is embossed into the carrier ply 1, but the
carrier ply 1 itself does not serve as a decorative ply.
[0098] FIG. 3 a third manufacturing stage 100c of the multilayer
element 100 formed from the second manufacturing stage 100b in FIG.
2, by the application to the replicating layer 4 of the layer 5 to
be structured. This layer 5 to be structured may be formed, for
example, as a metal layer, of silver or aluminum, for example,
which is applied by vapor deposition. The application of the layer
to be structured here is over the entire area. It is also possible,
however, for application to be envisaged only in a subregion of the
multilayer element 100, with the assistance, for example, of a
regionally shielding vapor deposition mask.
[0099] FIG. 4 shows a fourth manufacturing stage 100d of the
multilayer element 100 formed from the third manufacturing stage
100c in FIG. 3, by the application to the layer 5 to be structured
of a photoactivatable resist layer 6. In the present exemplary
embodiment, the resist layer 6 is formed as a positive resist,
i.e., as a resist in which the more strongly exposed (i.e.,
activated) regions are dissolved following exposure. The resist
layer 6 may be an organic layer applied by conventional coating
techniques, such as printing, pouring or spraying, in liquid form.
Provision may also be made for the resist layer 6 to be applied by
vapor deposition or to be laminated on as a dry film.
[0100] The photoactivatable layer 6 may be, for example, a positive
photoresist BAZ 1512 or AZ P 4620 from Clariant or S1822 from
Shipley, which is applied to the layer 5 to be structured in a
density per unit area of 0.1 g/m.sup.2 to 10 g/m.sup.2, preferably
of 0.1 g/m.sup.2 to 1 g/m.sup.2. The layer thickness is guided by
the desired resolution and by the operation. Application here is
envisaged over the entire area. Also possible, however, is
application only in a subregion of the multilayer element 100.
[0101] FIG. 5 shows a fifth manufacturing stage 100d of the
multilayer element 100, in which the multilayer element 100,
present after the fourth manufacturing stage 100d, is irradiated.
Electromagnetic radiation 7, having a wavelength suitable for
activating the photoactivatable resist layer 6, is radiated from
the second side 12 of the carrier film 1, i.e., the side of the
carrier film 1 that is opposite the carrier film 1 side coated with
the resist layer 6, through the multilayer element 100d. The
irradiation serves for activating the photoactivatable resist layer
6 in the second region 9, in which the decorative ply 3 has a
higher transmittance than in the first region 8. The strength and
duration of the exposure with the electromagnetic radiation 7 is
tailored to the multilayer element 100e in such a way that in the
second region 9 the radiation causes activation of the
photoactivatable resist layer 6, while in the first region 8
printed with the coating layer 31 it does not cause activation of
the photoactivatable resist layer 6. It has been found appropriate
if the contrast brought about by the coating layer 31 between the
first region 8 and the second region 9 is greater than two.
Moreover, it has been found appropriate if the coating layer 31 is
designed such that the radiation 7, after passing through the
entire multilayer element 100e, exhibits a ratio of the
transmittances, i.e., a contrast ratio, of approximately 1:2
between the first region 8 and the second region 9.
[0102] FIG. 6 shows a "developed" sixth manufacturing stage 100e of
the multilayer element 100 formed from the fifth manufacturing
stage 100d in FIG. 5, by the action of a developer solution, e.g.,
solvents or alkalis, more particularly a sodium carbonate solution
or a sodium hydroxide solution, having taken place on the surface
of the exposed photoactivatable resist layer 6 that is remote from
the carrier film 1. As a result of this, the exposed resist layer 6
has been removed in the second region 9. In the first region 8, the
resist layer 6 is intact, since the amount of radiation absorbed in
these regions has not led to sufficient activation. As already
mentioned, therefore, the resist layer 6 is formed from a positive
photoresist in the exemplary embodiment shown in FIG. 6. With a
photoresist of this kind, the more strongly exposed regions 9 are
soluble in the developer solution, e.g., in the solvent. In the
case of a negative photoresist, in contrast to this, the unexposed
or less strongly exposed regions 8 are soluble in the developer
solution, as set out below in the exemplary embodiment shown in
FIG. 9.
[0103] FIG. 7 shows a seventh manufacturing stage 100f of the
multilayer element 100 formed from the sixth manufacturing stage
100e in FIG. 6, by the removal of the layer 5 to be structured in
the second region 9 by means of an etchant. This is possible by
virtue of the fact that, in the second region 9, the layer 5 to be
structured is not protected against the attack of the etchant by
the developed resist layer 6, which acts as an etch mask. The
etchant may be, for example, an acid or an alkali. In this way, the
regions of the structured layer 5 that are shown in FIG. 7 are
formed.
[0104] FIG. 7a shows an eighth manufacturing stage 100g of the
multilayer element 100 formed from the seventh manufacturing stage
100f in FIG. 7, by further removal, likewise, of the regions of the
resist layer 6 that remained intact (this removal being referred to
as "stripping"). Generally speaking, the resist of the resist layer
6 has only low chemical stability, since it must be amenable to
attack by the developer solution in the present method. If the
intact regions of the resist layer 6 were left on the multilayer
element, therefore, it would be possible for the intact regions of
the resist layer 6 to have weakened the stability and resistance of
the security element, in the case, for example, of a counterfeiting
attack on the multilayer element using solvents or acids or
alkalis. As a result of the complete removal of the resist layer 6,
therefore, this disadvantage is avoided. The fact that certain
resists have only low chemical stability, i.e., are sensitive,
toward solvents, however, may also be exploited to advantage in
some cases. Following application of the multilayer element 100 to
a substrate, more particularly to the surface of a security
document, the resist is washed off by means of solvent, together
with a dye that colors the resist, in the event of attempted
manipulations. The attempted manipulation is made visible by a
change in the coloredness of the resist.
[0105] In this way, therefore, the layer 5 to be structured can be
structured in register with the first and second regions 8 and 9
defined by the coating layer 31 without additional technical cost
and complexity. In conventional methods for producing an etch mask
by means of mask exposure, the mask being present either as a
separate unit, e.g., as a separate film or as a separate glass
plate/glass roller, or in the form of a layer applied subsequently
by printing, the problem occurs that linear and/or nonlinear
distortions in the multilayer element 100, brought about by prior
operating steps, more particularly those involving thermal and/or
mechanical stress, as for example when the replicating structure 42
is produced in the replicating layer 4, cannot be compensated
entirely over the entire area of the multilayer element 100,
despite the fact that mask orientation takes place to register
marks that are present in disposition preferably on the horizontal
and/or vertical edges of the multilayer element. The tolerance here
fluctuates within a comparatively large range over the entire area
of the multilayer element 100.
[0106] With the method of the invention, the first and second
regions 8 and 9 defined by the coating layer 31 are utilized as a
mask, with the coating layer 31 being applied in an early
operational step in the production of the multilayer element 100 as
described above. As a result of this, there can be no additional
tolerances and also no additional tolerance fluctuations over the
area of the multilayer element 100, since the subsequent generation
of a mask and the resultant requirement for extremely in-register
subsequent positioning of this mask independent of the operational
profile so far are avoided. The tolerances and register accuracies
in the case of the method of the invention have their basis only in
the not absolutely precise profile of the color edge of the first
and second regions 8 and 9, defined by the coating layer 31, the
quality of these regions being determined by the printing technique
employed in each case, and are situated, for instance, in the
micrometer range, and hence well below the resolution capacity of
the eye; in other words, the naked human eye is no longer able to
perceive tolerances present.
[0107] The multilayer element 100 shown in FIG. 8a is formed from
the manufacturing stage 100g of the multilayer element 100, shown
in FIG. 7a, by the application of a compensating layer 10 to the
exposed structured layer disposed in the first region 8 and also to
the replicating layer 4 disposed in the second region 9, and
exposed by removal of the layer 5 to be structured and of the
photoresist layer 6. Here, the compensating layer 10 is applied
over the full area.
[0108] It is possible for the compensating layer 10 to be applied
in a different layer thickness in each of the first and second
regions 8 and 9 respectively, by means of knifecoating, printing or
spraying, for example, so that the compensating layer 10 has a
planar, substantially structureless surface on its side remote from
the carrier ply 1. The layer thickness of the compensating layer 10
varies, since it compensates/evens out the different levels of the
structured layer 5 disposed in the first region 8, and the
replicating layer 4 exposed in the second region 9. In the second
region 9, the thickness of the compensating layer 10 is selected
greater than the thickness of the structured layer 5 in the first
region 8, and so the side of the compensating layer 10 that is
remote from the carrier ply 1 has a planar surface. Also possible,
however, is the application of the compensating layer 10 only in a
subregion of the multilayer element 100. It is possible for one or
more further layers, such as an adhesion layer or adhesive layer
for example, to be applied to the planar compensating layer 10. In
an advantageous way it is also possible for the adhesion layer or
adhesive layer to take on the level-compensating effect of the
compensating layer 10, with the consequence that there is no need
for a separate compensating layer 10.
[0109] FIG. 8b shows an alternative design of the multilayer
element 100 shown in FIG. 8a, formed from the manufacturing stage
100f of the multilayer element 100, shown in FIG. 7a, by the
application of a compensating layer 10 to the regions of the resist
layer 6 that were retained in the first region 8, and also to the
replicating layer 4 disposed in the second region 9 and exposed by
removal of the layer 5 to be structured and of the photoresist
layer 6. In contrast to the multilayer element 100 shown in FIG.
8a, therefore, the multilayer body shown in FIG. 8b comprises the
retained regions of the resist layer 6.
[0110] FIG. 9 shows an alternatively formed multilayer element 100'
of the invention, in which, in contrast to the multilayer element
100 shown in FIG. 8, a negative resist layer 6 rather than a
positive resist layer 6 has been used. As a result, the structured
layer 5 and the resist layer 6 are disposed not like the coating
layer 31 in the first region 8, but instead in the second region 9.
The structured layer 5 and the resist layer 6 of the alternative
multilayer element 100' are indeed disposed in register with the
regional boundaries of the regions 8, 9 of the coating layer 31,
like the multilayer element 100 shown in FIG. 8, but are not
disposed congruently with the coating layer 31, but instead are
disposed in the unprinted interstices 9 of the coating layer
31.
[0111] FIG. 10 shows a multilayer element 100'', in which the
decorative ply 3 consists of a regionally formed coating layer 31,
which is disposed on the second side 12 of the carrier film 1, with
the second side 12 being opposite the first side 11 of the carrier
film 1, on which the structured layer 5 is disposed.
[0112] FIG. 11a to FIG. 11g show in schematic representation
different inventive designs of the decorative ply 3. Shown in each
case is a carrier film 1 having a bottom side and a top side, on
which is disposed a decorative ply 3 comprising a first region 8
and/or a second region 9 in different dispositions. In all of the
designs shown, the top side may be either the first side or the
second side of the inventive multilayer element.
[0113] When reference is made below to a "first coating layer" and
a "second coating layer", what this means is that there are two
differently formed coating layers, with, for example, different
optical properties such as color and/or different mechanical
properties such as elasticity modulus, having different
transmittances. Two first coating layers, explicitly described as
having a different layer thickness from one another, likewise have
a different transmittance. Absent an explicit description to the
effect that two layer elements of a first coating layer have
differing layer thicknesses, the assumption shall be that they are
of equal thickness and have the same transmittance.
[0114] FIG. 11a shows the version already depicted in FIG. 10, in
which the decorative ply 3 consists of a first coating layer 31
which is disposed in the first region on the top side of the
carrier film 1 and is not present in the second region 9.
[0115] FIG. 11b shows a version in which the decorative ply 3
consists of a first coating layer 31 disposed over the full area of
the top side of the carrier film 1 and having a greater thickness
in the first region 8 than in the second region 9.
[0116] FIG. 11c shows a version in which the decorative ply 3
consists of a first coating layer 31 disposed in the first region 8
on the top side of the carrier film 1, and of a second coating
layer 32 disposed in the second region 9 likewise on the top side
of the carrier film 1. The coating layers 31 and 32 may, for
example, be two different colored coating layers or two coating
layers each having different optical effects.
[0117] FIG. 11d shows a version in which the decorative ply 3
consists of a first coating layer 31 which is disposed in the first
region 8 and which is not present in the second region 9. The first
coating layer comprises two layer components, a first layer
component being disposed on the top side of the carrier film 1 and
a second layer component being disposed on the bottom side of the
carrier film 1.
[0118] FIG. 11e shows a version in which the decorative ply 3 from
a first coating layer 31 which is disposed in the first region 8 on
the top side of the carrier film 1 and has a first thickness, and
from a first coating layer 31 which is disposed in the second
region 9 on the bottom side of the carrier film 1 and has a second
thickness, which is lower than the first thickness.
[0119] FIG. 11f shows a version in which the decorative ply 3
consists of a first coating layer 31, which is disposed in the
first region 8 on the top side of the carrier film 1, and of a
second coating layer 32, which is disposed in the second region 9
on the bottom side of the carrier film 1.
[0120] FIG. 11g shows a version in which the decorative ply 3
consists of a first coating layer 31, which is disposed in the
first region 8 on the top side of the carrier film 1, and of a
second coating layer 32, which is disposed over the full area of
the bottom side of the carrier film 1.
[0121] FIG. 12 shows a multilayer element 100''', in which the
decorative ply 3 is formed by a first coating layer 31, which
generates a first color impression, and a second coating layer 32,
which generates a second color impression, both coating layers 31,
32 being disposed on the same side of the carrier ply 1 between the
functional layer 2 and the replicating layer 4.
[0122] FIG. 13 shows a multilayer element 100a' in which the
decorative ply 3 is formed from a first, regionally applied coating
layer 31 and from a second coating layer 32, applied over the full
area of said first layer 31, with both coating layers 31, 32 being
disposed on the same side of the carrier ply 1.
[0123] FIG. 14 shows a multilayer element 100a'', in which the
decorative ply 3 consists of a first coating layer 31, which is
applied over the full area of the second side 12 of the carrier
film 1, and of a second coating layer 32, which is applied
regionally on the first side 11 of the carrier film 1.
[0124] FIG. 15 shows transmission spectra of four different classes
of UV absorbers which may be present in the first region 8 of the
decorative ply 3, in order to form a different transmittance in the
first region 8 and in the second region 9. The UV absorbers are
present at a concentration of 0.00014 mol/l in chloroform. The plot
shows the transmittance % T, measured as a percentage, over the
wavelength .lamda. in the range from 280 to 410 nm. The dash-dot
line A shows the transmission of oxalanilide, the dash-dot-dot line
B the transmission of hydroxybenzophenone, the dash-dash line C the
transmission of hydroxyphenyl-S-triazine, and the continuous line D
the transmission of benzotriazole.
LIST OF REFERENCE NUMERALS
[0125] 1 carrier ply [0126] 1a, 1b, 1c layers (of 1) [0127] 2
functional layer [0128] 3 decorative ply [0129] 4 replicating layer
[0130] 5 layer to be structured, or structured layer [0131] 6
resist layer [0132] 7 radiation [0133] 8 first region [0134] 9
second region [0135] 10 compensating layer [0136] 11 first side (of
1) [0137] 12 second side (of 1) [0138] 31 first coating layer (of
3) [0139] 32 second coating layer (of 3) [0140] 33, 34 coloration
[0141] 40 surface (of 4) [0142] 41 first zone, unstructured (of 4)
[0143] 42 second zone, structured (of 4) [0144] 100 multilayer
element
* * * * *